Our bodies consist of 206 bones that have a primary function to provide support. The bones are also important for storing minerals and producing new blood cells. Although diseases of the bone are not a common primary source of morbidity, they do affect millions of people in the United States, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases.
Congenital
Congenital bone diseases are those present at birth, usually caused by a genetic mutation. A mutation is an accidental change in a gene that results in the deletion or malformation of a required protein.
Osteogenesis imperfecta (OI), also known as brittle bone disease, is an inherited disease caused by a mutation in the gene that codes for collagen. Collagen is the major protein found in connective tissues, cartilage and bones. Those suffering from OI may have weak muscles, brittle teeth, a curved spine, hearing loss and bones that break even in the absence of any trauma.
Osteopetrosis is also a congenital disease in which the osteoclasts, the specialized cells responsible for bone resorption, are not functioning properly. In people with osteopetrosis, there is an imbalance in the bone remodeling cycle and while the osteoclasts are not working the osteoblasts are still producing new bone. This creates bones that are dense yet fragile and have very little space for the marrow. Patients may experience frequent fractures, frequent infections due to lack of bone marrow, hearing loss, vision impairments and strokes.
Acquired
Some bone diseases are acquired, meaning they develop as a result of environmental, nutritional or unknown factors. Aseptic necrosis, also called avascular necrosis, is the death of bone tissue caused by a lack of blood flow. The blood flow may be blocked by a broken bone or long-term use of steroids or alcohol that can inhibit blood flow causing bone death.
Cancer, the abnormal growth of cells, is often caused by environmental factors creating mutations in genes. Although rare, accounting for less than 1 percent of all cancers according to the National Cancer Institute, there are several types of primary bone cancer, that is, cancers that begin in the bone tissues. These include osteosarcoma that begins in the hard tissue, chondrosarcoma that begins in the cartilage tissues, and Ewing sarcoma that begins in the soft tissues.
Metabolic
Metabolic bone diseases are those that are caused by a dysfunction in proteins, enzymes or hormones in the body. The most well-known metabolic bone disease is osteoporosis which is caused by several factors including hormone deficiency. Osteoporosis affects 10 million people in the U.S., 8 million of whom are women as reported by the American College of Rheumatology. Those with osteoporosis have a loss of bone mass causing bones to be weak and fragile.
Paget's disease is a disorder of the bone that results in deformed and brittle bones. The exact cause of the disease is unknown, but a variety of environmental factors may contribute to the development of the disease.
Osteomalacia is a metabolic bone disease characterized by a lack of minerals including calcium and phosphorus. This disease can cause bone pain, fatigue and malaise.
